Differentiating between Gas and Vapour:

Gas:
- Gas is a state of matter that is characterized by its ability to fill the entire space available to it.
- Gases have no definite shape or volume and can expand indefinitely.
- They have weak intermolecular forces and particles move freely in all directions.
- Examples of gases include oxygen, nitrogen, carbon dioxide, and helium.

Vapour:
- Vapour is the gaseous state of a substance that is usually a liquid or solid at room temperature and pressure.
- Vapour is formed when a liquid or solid substance evaporates or sublimes.
- Unlike gases, vapours have a definite shape and volume, but they can still expand and fill the container they are in.
- Vapours have stronger intermolecular forces compared to gases due to the presence of the original substance's molecules.
- Examples of vapours include steam (water vapour), gasoline vapour, and alcohol vapour.

Differentiating Factors:

Formation:
- Gases are formed directly from their gaseous state or by the evaporation of liquids or sublimation of solids.
- Vapours are formed by the evaporation or sublimation of liquids or solids that are usually in their condensed states at room temperature.

State of Matter:
- Gases can exist as gases at room temperature and pressure.
- Vapours are the gaseous state of substances that are usually liquids or solids at room temperature and pressure.

Intermolecular Forces:
- Gases have weak intermolecular forces between their particles.
- Vapours have stronger intermolecular forces due to the presence of the original substance's molecules.

Shape and Volume:
- Gases have no definite shape or volume and can expand indefinitely.
- Vapours have a definite shape and volume, but they can still expand and fill the container they are in.

Examples:
- Examples of gases include oxygen, nitrogen, carbon dioxide, and helium.
- Examples of vapours include steam (water vapour), gasoline vapour, and alcohol vapour.

Summary:
In summary, gases and vapours differ in their formation, state of matter, intermolecular forces, shape, and volume. Gases exist as gases at room temperature and pressure and have weak intermolecular forces, while vapours are the gaseous state of substances that are usually liquids or solids at room temperature and pressure and have stronger intermolecular forces. Gases have no definite shape or volume, while vapours have a definite shape and volume but can still expand.

The word vapour is used to describe those gases that usually exist at liquid at room temperature waterparticles in gaseous state are called vapour oxygen at room temperature exit gas particles.